1. Field of the Invention
The present invention relates to a fatigue-resistant polyimide resin composition and an injection molded article of the same, and more particularly relates to a polyimide resin composition having good melt-processing ability and excellent fatigue resistance and an injection molded article obtained from the polyimide resin composition.
2. Description of the Related Art
Conventionally, polyimide has a high heat resistance, excellent mechanical strength and outstanding dimensional stability and additionally has flame retardance and electrical insulation property. Thus, polyimide has been widely used in the fields of electric and electronic appliances, space and aeronautic equipment and transport machinery. Various kinds of polyimides which exhibit excellent properties have been conventionally developed. However, some polyimide has no distinct glass transition temperature although heat resistance is excellent, and must be processed with specialized techniques such as sinter molding in the case of being used as a molded material. Other polyimide is excellent in processing ability. On the other hand, such polyimide has a low glass transition temperature and additionally is soluble in halogenated hydrocarbon solvents, and is unsatisfactory in view of resistance to heat and solvent. Thus, conventional polyimide has exhibited both merits and drawbacks in terms of properties.
In order to solve these problems, the present inventors have developed polyimide and various copolyimides which can be melt-processed and are excellent in mechanical strength, heat resistance, electrical property and chemical resistance (Japanese Laid-Open Patent SHO 61-143478 and HEI 3-47837). However, dynamic mechanical properties such as fatigue property have not been examined to a great extent and almost no information can be found under the existing circumstances in the fields of an injection-moldable high-heat-resistance polyimide which has been developed particularly in recent years.